1. Field of the Invention
This invention relates to an anti-roll stabilizer system for a motor vehicle.
2. Description of Related Art
Torsional stabilizer bars have proven useful in vehicles for many years. Such stabilizer bars commonly employ a transverse torsion bar segment pivotally attached to the vehicle chassis and leading or trailing longitudinal segments attached to a control arm or wheel carrier. Examples of stabilizer bars having this particular configuration are shown in U.S. Pat. No. 4,206,935, which discloses several stabilizer bars capable of preferentially coupling the road wheels of a common axle together in a manner such that when one of the road wheels differs in level from the other due to a cornering maneuver the vehicle body will be prevented from excessive rolling or leaning to either side by the torsional resistance produced in the stabilizer bar.
U.S. Pat. No. 3,197,233 discloses a stabilizer system in which a bifurcated stabilizer bar is loaded torsionally by a hydraulic motor joining the two furcations. This system is limited because it requires an external pump driven by the vehicle's engine. It is further limited because torsional bias can be applied only when the vehicle is in a leaning situation; application of the bias when the vehicle is operating in the straight-ahead mode will cause the body to roll to one side. This necessarily limits the flexibility of the control strategy of the device. In addition, this device as well as the devices disclosed in U.S. Pat. No. 4,206,935 will degrade ride quality in many cases. This occurs because the stabilizer couples the wheels together. When one wheel strikes a raised obstruction in the roadway during straight running, the body will therefore tend to roll more than were no stabilizer bar included in a suspension system.
U.S. Pat. No. 4,337,958 discloses a suspension for a snowmobile having a stabilizer bar linked to both skis of the front suspension of a snowmobile. The action of the stabilizer bar is dampened by resilient yieldable means connected to a mid portion of the stabilizer bar. This system, of course, suffers from at least one of the drawbacks of the previously discussed systems inasmuch as the stabilizer couples both the left and right suspensions together.
The present invention utilizes a torsion bar or spring as a stabilizer element. Those skilled in the art will appreciate that torsion bars have been used in automotive suspensions in various ways for many years.
German Auslegeschrift No. 1,160,313 discloses a torsion bar suspension spring including a hydraulic cylinder for adjusting the static preload upon the torsion bar.
U.S. Pat. No. 4,010,941 discloses a stabilizer bar suspension for a military vehicle in which the working length of the stabilizer bar is adjustable to accommodate various vehicle loads.
The inhibition of excessive tilting or roll of the vehicle body in cornering maneuvers has been achieved by designers of suspension systems in which hydraulic or pneumatic cylinders directly support the vehicle body at each wheel position. Such suspension systems have included the ability to counteract excessive leaning of the body during cornering maneuvers. Examples of suspensions of this type are disclosed in U.S. Pats. Nos. 3,608,925; 3,893,680; and 4,361,346. The cost of these systems, however, would be expected to be quite high because components which must support the weight of the vehicle body and chassis must necessarily be of heavier construction and would also consume considerable power to function so as to provide roll control on a real time basis during vehicle operation.
U.S. Pat. No. 3,995,883 discloses yet another suspension arrangement in which a variable suspension damper is controlled by a microprocessor to produce desired ride characteristics. This suspension damper is coupled directly between the vehicle body or chassis and the balance of the suspension.
It is an object of the present invention to provide an anti-roll stabilizer system for a motor vehicle which will independently control each of the wheels to which it is applied.
It is a further object of the present invention to provide an anti-roll stabilizer system for a motor vehicle which will operate at a relatively low power level.
It is also a further object of the present invention to provide an anti-roll stabilizer system that is simple in terms of its design and construction and low in system weight.
It is a still further object of the present invention to provide an anti-roll stabilizer system which will not degrade vehicle ride when the vehicle is running straight ahead.